Toluene-Ethanol Solution of Polyvinyl Butyral and Nonsolvent-Induced Phase Separation
-
摘要: 在片式多层陶瓷电容器（MLCC）的流延工艺中，甲苯-乙醇混合溶剂是黏合剂聚乙烯醇缩丁醛（PVB）广泛采用的溶剂体系。本文探讨了甲苯与乙醇的体积比、PVB浓度以及流延成膜的相对湿度等因素对溶液中PVB构象以及凝聚态膜片结构的影响。PVB中存在由烷侧链排列形成的玻璃区以及由链缠结而成的无定形区。乙醇是PVB的良性溶剂，通过溶胀玻璃区，使得PVB链更加舒展；甲苯可以有效降低PVB与溶液的摩擦，并通过“成核-生长”机制发生粗化聚并，导致分子间相互作用逐渐增大。较高湿度会造成膜片缺陷；混合溶剂中乙醇的体积分数过高易形成缺陷；缺陷几乎不影响膜的有效模量以及热力学性能。Abstract: The emergency of micro/nanoelectronic systems and miniaturized portable devices raises urgent demand on miniaturized and integrated multi-layer ceramic capacitors (MLCC). For MLCC fabrication, tape-casting technology is one of the key processes, where routinely using toluene-ethanol solution of polyvinyl butyral (PVB) as a binder. Thus, the solution properties and their gelation play crucial roles in suppressing the flaws (e.g., pinhole and local heterogeneity) in the dielectric layer. However, the effects of volume ratio of toluene to ethanol have yet been investigated in detail. This work decouples the effects of toluene and ethanol on the intermolecular, intramolecular and PVB-solvents interactions, and further understands the effects of solution’s compositions on gelation process. It is found that ethanol is a good solvent of PVB, through the expansion of the glassy region as structured by the packing of alkyl side chains, while toluene can effectively reduce the friction between PVB chains and solvents. Upon being exposed to atmosphere, PVB in solutions undergoes coarsening and coalescence through "nucleation-growth" mechanism. When the relative humidity is low in atmosphere, the compositional trajectory cannot cross the binodal curve and thus produce dense morphology, while high relative humidity will cause defects because the compositional trajectory crosses the binodal or spinodal curves. The defects almost do not affect the effective modulus of PVB film and thermomechanical properties. This work provides reference significance for screening PVB polymer, solvent system and film forming conditions in MLCC casting process.
-
Key words:
- multi-layer ceramic capacitor /
- polyvinyl butyral /
- solubility /
- phase separation /
- humidity
-
图 1 PVB的分子结构及相关物性：（A）PVB粉末体系的分子结构信息； （B） DSC和TGA曲线（N2，10 ℃/min）； （C） XRD衍射峰：低角(7.6°)反映主链之间的距离，高角 (19.3°) 反映了侧链之间的距离；（D） 分子链示意图
Figure 1. The molecular structure and related properties of PVB : (A) Molecular structure information of PVB powder; (B) DSC and TGA curves (N2, 10 ℃/min); (C) XRD diffraction peak: The low angle (7.6°) reflects the distance between main chains and the high angle (19.3°) reflects the distance between side chains; (D)Schematic diagram of molecular chain
图 2 PVB溶液的热力学和动力学：（A）PVB粉末体系与不同体积比的甲苯-乙醇体系的比较溶度参数（红线：PVB的溶度参数；黑线：溶液的溶度参数） ; （B）溶液黏度（η）（测试方法：同轴圆筒）；（C）回旋半径（Rg）和均方末端距（h）随甲苯-乙醇体积比的变化；（D）增比黏度随 ρ/ρ* 变化；（E）增比黏度随 ρ/ρ * 变化的幂律关系； （F）不同甲苯-乙醇体积比的标度值
Figure 2. Thermodynamics and kinetics of PVB solution: (A) Solubility parameters of PVB powder, compared with different ratios of toluene-ethanol solutions. (Red line: the polarity solution parameter of the PVB；Black line: non-polar solution parameter of PVB); (B) Viscosity (η) of solutions (test method : Coaxial cylinder); (C) Radius of gyration （Rg） and the mean square end distance （h） change with the volume ratio of toluene to ethanol; (D) The specific viscosity changes with ρ/ρ*; (E) Power law relationship of the specific viscosity changing with ρ/ρ * ; (F) Scale value of different volume ratio of toluene to ethanol
图 3 （A）聚合物-溶剂-非溶剂的三元相图：绿色实线表示混合物的分离线，蓝色渐变色区域表示“玻璃状”区域，橙色线表示混合物分离的平衡线，棕色虚线箭头表示富聚合物相； （B） 浊点实验绘制的PVB-乙醇-甲苯三元相图；（C） 将甲苯滴加到 PVB 乙醇溶液中（溶液的浊度表明聚合物溶液的相分离）
Figure 3. (A) Schematic diagram of polymer-solvent-non-solvent ternary phase diagram: the green solid line indicates the separation line of the mixture, and the blue gradient color area indicates the "glassy" area, the orange line indicates the equilibrium line of the mixture separation, and the brown dashed arrow indicates the polymer-rich phase; (B) PVB-ethanol-toluene ternary phase diagram drawn by the cloud point experiment; (C) Toluene was added by titration to the PVB ethanol solution (The turbidity of the solution indicates the phase separation of the polymer solution)
图 4 PVB-混合溶剂滴定实验及SEM图像：（A）PVB-混合溶剂-H2O三元相图示意图； （B） 滴定前后照片对比； （C）和（D）分别为PVB胶团在劣溶剂和良溶剂中的SEM图像
Figure 4. Titration experiment of PVB-mixed solvent and SEM images: (A) Schematic diagram of PVB-mixed solvent-H2O ternary phase diagram; (B) Comparison of photos before and after titration; (C) and (D) are the SEM images of PVB in poor solvent and good solvent, respectively
图 5 不同湿度下，不同PVB溶液流延成膜研究：（A）VIPS成膜过程示意图； （B） PVB/甲苯-乙醇溶剂-水三元相图及其在不同湿度下的组分轨迹图（蓝色虚线代表极低相对湿度，粉色虚线代表中等相对湿度，橙色虚线代表高湿度下的成分轨迹）； （C） 在较高相对湿度下形成的 PVB 膜的 SEM 图像；（D） 高相对湿度下形成的薄膜的孔壁厚度（hT）和孔隙率与溶剂比例的关系； （E） 在较低相对湿度下形成的 PVB 膜的 SEM 图像
Figure 5. Study on casting film formation of different PVB solutions under different humidity: (A) Schematic diagram of VIPS film formation process; (B) PVB/toluene-ethanol solvent/water ternary phase diagram and its component trajectory diagram under different humidities (the blue dotted line represents the extremely low relative humidity, the pink dotted line represents the medium relative humidity, and the orange dotted line represents the composition trajectory under high humidity); (C) SEM images of the PVB film formed under high relative humidity; (D) Relationship between the pore wall thickness and porosity of the membrane formed under higher humidity with the proportion of solvent; (E) SEM images of the PVB film formed under lower relative humidity
图 6 相对温度（A）较高或（B）较低时，不同比例溶剂成膜的应力-应变曲线； 在相对温度（C）较高或（D）较低条件下形成的薄膜的杨氏模量
Figure 6. Under (A) high humidity and (B) low humidity film forming conditions, the stress and strain curves of different proportions of solvent film formation; Young's modulus of the film formed under (C) high humidity and (D) low humidity conditions
表 1 各基团的摩尔引力常数与摩尔体积
Table 1. Molar gravitational constant and molar volume of each group
Group Gravitational constant /(${\rm{cal}}^{\frac {1}{2}}\cdot{\rm{cm}}^{\frac {3}{2}} $·mol−1) Molar volume/(cm3·mol−1) ―CH3 148.3 33.5 ―CH2― 131.5 16.1 >CH― 86.0 −1.0 ―O―（Ether，Acetal） 115.0 3.8 ―OH 225.8 10.0 
下载: 导出CSV
表 2 不同体积比溶剂的溶度参数
Table 2. Solubility parameters of solutions in different volume fractions
V
（Toluene）∶V（EtOH）$ \delta $/（${ {\rm{cal} } }^\frac{1}{2}\cdot{\rm{c} }{ {\rm{m} }^{ - \frac{3}{2} } }$） ω1/（${ {\rm{cal} } }^\frac{1}{2}\cdot{\rm{c} }{ {\rm{m} }^{ - \frac{3}{2} } }$） Ω1/（${\rm{cal} } ^\frac{1}{2}$·${\rm{cm} } ^{-\frac{3}{2} }$） 4∶1 10.06 2.35 9.78 1∶1 11.34 4.15 10.54 1∶4 12.24 5.67 10.84 1∶9 12.47 6.13 10.86
下载: 导出CSV
-
[1] LI J L, SHEN Z H, CHEN X H, YANG S, ZHOU S L, WANG M W, WANG L H, KOU Q W, LIU Y C, LI Q, XU Z, CHANG Y F, ZHANG S J, LI F. Grain-orientation-engineered multilayer ceramic capacitors for energy storage applications [J]. Nature Materials,2020,19(9):999-1005. doi: 10.1038/s41563-020-0704-x [2] 罗凌虹, 周和平, 黄河激, 王少洪. 多层片式电感器介质材料及其工艺的发展现状 [J]. 无机材料学报,2001,16(6):1032-1040. doi: 10.3321/j.issn:1000-324X.2001.06.002LUO L H, ZHOU H P, HE H J, WANG S H. Development of dielectric materials and processing for mulitilayer chip inductors [J]. Journal of Inorganic Materials,2001,16(6):1032-1040. doi: 10.3321/j.issn:1000-324X.2001.06.002 [3] XIANG J H, HUANGY, XIE Z P. Study of gel-tape-casting process of ceramic materials [J]. Materials Science and Engineering A: Structural Materials Properties Microstructure and Processing,2002,323:336-341. doi: 10.1016/S0921-5093(01)01390-9 [4] WANG H, LIU B, WANG X. Effects of dielectric thickness on energy storage properties of surface modified BaTiO3 multilayer ceramic capacitors [J]. Journal of Alloys and Compounds,2020,817:152804. doi: 10.1016/j.jallcom.2019.152804 [5] YOON D H, LEE B I. Processing of barium titanate tapes with different binders for MLCC applications: Part II. Comparison of the properties [J]. Journal of the European Ceramic Society,2004,24(5):753-761. doi: 10.1016/S0955-2219(03)00334-0 [6] 张晶. MLCC中甲苯替代溶剂的研究[D]. 长春: 吉林大学, 2010.ZHANG J. The research on the organic solvent for replacing toluene in MLCC[D]. Changchun: Jilin University, 2010. [7] BITTERLICH B, HEINRICH J G. Aqueous tape casting of silicon nitride [J]. Journal of the European Ceramic Society,2002,22(13):2427-2434. doi: 10.1016/S0955-2219(02)00029-8 [8] RUBINSTEIN M, SEMENOV A N. Dynamics of entangled solutions of associating polymers [J]. Macromolecules,2001,34(4):1058-1068. doi: 10.1021/ma0013049 [9] DANIELSEN S P O, BEECH H K, WANG S, BASSIL M E Z, WANG X D, LIEL S, TETSU O, WANG Z, PATRICIA N J, HU Y X, DAVID J L, GEORGI S, STEPHEN L C, JEREMIAH A J, JULIA A K, BRADLEY D O, MICHAEL R. Molecular characterization of polymer networks [J]. Chemical Reviews,2021,121(8):5042-5092. doi: 10.1021/acs.chemrev.0c01304 [10] MARTINEZ N C D V, DINIC J, LU X, WANG C, REZA R, HAO S, VIVEK S. Rheology and pinching dynamics of associative polysaccharide solutions [J]. Macromolecules,2021,54(13):6372-6388. doi: 10.1021/acs.macromol.0c02751 [11] 曹秀华, 姚卿敏. 水性黏合剂在电子陶瓷流延成型中的应用 [J]. 电子元件与材料,2005,24(6):57-59. doi: 10.3969/j.issn.1001-2028.2005.06.018CAO X H, YAO Q M. Application of aqueous binder in electronic ceramic tape-casting [J]. Electronic Components and Materials,2005,24(6):57-59. doi: 10.3969/j.issn.1001-2028.2005.06.018 [12] LI M Y, KATSOURAS I, PILIEGO C, GUNNAR G, INGO L, PAUL W M B, DAGO M L. Controlling the microstructure of poly(vinylidene-fluoride) (PVDF) thin films for microelectronics [J]. Journal of Materials Chemistry C,2013,1(46):7695-7702. doi: 10.1039/c3tc31774a [13] DSUEK K. Phase separation during the formation of three-dimensional polymers [J]. Journal of Polymer Science Part B:Polymer Letters,1965,3(3):209-212. doi: 10.1002/pol.1965.110030311 [14] LIN K Y, WANG D M, LAI J Y. Nonsolvent-induced gelation and its effect on membrane morphology [J]. Macromolecules,2002,35(17):6697-6706. doi: 10.1021/ma020073y [15] BOUYER D, POCHAT-BOHATIER C. Validation of mass-transfer model for VIPS process using in situ measurements performed by near-infrared spectroscopy [J]. AIChE Journal,2013,59(2):671-686. doi: 10.1002/aic.13839 [16] 何曼君, 张洪东, 陈维孝. 高分子物理[M]. 上海: 复旦大学, 2006.HE M J, ZHANG H D, CHEN W X. Polymer Physics[M]. Shanghai: Fudan University, 2006. [17] LIAU L C K, VISWANATH D S. Thermal degradation of poly(vinylbutyral)/ceramic composites: A kinetic approach [J]. Industrial & Engineering Chemistry Research,1998,37(1):49-57. [18] LOPEZ-BARRON C R, TSOU A H, HAGADOM J R, JOSEPH A T. Highly entangled α-Olefin molecular bottlebrushes: Melt structure, linear rheology, and interchain friction mechanism [J]. Macromolecules,2018,51(17):6958-6966. doi: 10.1021/acs.macromol.8b01431 [19] PAN J G, GAO L, SUN W X, WANG S, SHI X T. Length effects of short alkyl side chains on phase-separated structure and dynamics of hydrophobic association hydrogels[J]. Macromolecules , 2021 54(13): 5962-5973. [20] MIYAZAKI T, YAMAOKA K, GONG J P, YOSHIHITO O. Hydrogels with crystalline or liquid crystalline structure [J]. Macromolecular Rapid Communications,2002,23(8):447-455. doi: 10.1002/1521-3927(20020501)23:8<447::AID-MARC447>3.0.CO;2-O [21] 刘双, 曹晓, 张嘉琪, 韩迎春, 赵欣悦, 陈全. 流变技术在高分子表征中的应用: 如何正确地进行剪切流变测试 [J]. 高分子学报,2021,52(4):406-422. doi: 10.11777/j.issn1000-3304.2020.20230LIU S, CAO X, ZHANG J Q, ZHAO X Y, CHEN Q. Toward correct measurements of shear rheometry [J]. Acta Polymerica Sinica,2021,52(4):406-422. doi: 10.11777/j.issn1000-3304.2020.20230 [22] 李岗严. 高分子溶液[M]. 北京: 科学出版社, 2014.TERAOKE I. Polymer Solution[M]. Beijing: Science Press, 2014. [23] LANG C, LANASA J A, UTOMO N, XU Y, NELSON M J, SONG W, HICKNER M A, COLBY R H, KUMAR M, HICKEY R J. Solvent-non-solvent rapid-injection for preparing nanostructured materials from micelles to hydrogels [J]. Nature Communications,2019,10(1):3855. doi: 10.1038/s41467-019-11804-7 [24] VENAULT A, CHANG Y, WANG D M, BOUYER D. A review on polymeric membranes and hydrogels prepared by vapor-induced phase separation process [J]. Polymer Reviews,2013,53(4):568-626. doi: 10.1080/15583724.2013.828750 [25] MATSUYAMA H, TERAMTTO M, NAKATANI R, TAISUKE M. Membrane formation via phase separation induced by penetration of nonsolvent from vapor phase: I. Phase diagram and mass transfer process [J]. Journal of Applied Polymer Science,1999,74(1):159-170. doi: 10.1002/(SICI)1097-4628(19991003)74:1<159::AID-APP20>3.0.CO;2-S [26] MTENUT P, SU Y S, CHINPA W. A top surface liquid layer during membrane formation using vapor-induced phase separation (VIPS)—Evidence and mechanism of formation [J]. Journal of Membrane Science,2008,310(1-2):278-288. doi: 10.1016/j.memsci.2007.11.016 -
点击查看大图
计量
- 文章访问数: 872
- HTML全文浏览量: 381
- PDF下载量: 169
- 被引次数: 0
